Print ribbon drive and reversing device

ABSTRACT

Print ribbon feed apparatus embodies a translator for alternately applying drive in opposite directions to one of a pair of print ribbon spools and includes mechanism to responsively remove drive from the wound spool and to apply drive to the unwound spool.

United States Patent Inventor Donald L. Bumgardner Union Lake, Mich.

Appl. No. 9,153

Filed Feb. 6, 1970 Patented Jan. 11, 1972 Assignee Burroughs Corporation Detroit, Mich.

PRINT RIBBON DRIVE AND REVERSING DEVICE 6 Claims, 7 Drawing Figs.

US. Cl 242/67.4, 40/93, 197/162, 242/158.4

Int. Cl ..B65h 17/02, B41j 33/22, B41j 33/51 Field 01' Search 242/67.4,

[56] References Cited UNITED STATES PATENTS 2,159,727 5/1939 Markley, .Ir. 242/67.4 UX 833,287 10/1906 Alexander 197/162 762,266 6/1904 Alexander 197/162 568,299 9/1896 Ellis et a1. 242/1583 X FOREIGN PATENTS 461,764 [/1914 France 40/93 Primary Examiner-George F. Mautz Assistant Examiner-Milton Gerstein Auorneys- Kenneth L. Miller and Edwin W. Uren ABSTRACT: Print ribbon feed apparatus embodies a translator for alternately applying drive in opposite directions to one of a pair of print ribbon spools and includes mechanism to responsively remove drive from the wound spool and to apply drive to the unwound spool.

PATENTEB JAN! 1 B72 FIG.I

SHEET 1 [1F 2 1 N VE N TOR.

DONALD L. BUMGARDNER AGENT PATENTEU mu 1 i972 SHEEI 2 OF 2 nov T mw m PRINT RIBBQN DRIVE AND REVERSING DEVICE BACKGROUND OF THE INvention Prior art discloses print-ribbon-reversing devices including drive worms which screw themselves out of engagement with associated worm wheels when wheel rotation is halted by maximum ribbon transfer, and including also detents which secure the engagement of worms and worm wheels that are associated with ribbon spools onto which the ribbon is being wound. Such devices commonly rely on the detent mechanism to supply all of the force that is required to fully engage the opposite ribbon spool drive during the reversing process. This force, which must be relatively high, is supplied by resilient means and is thus inconstant over the range of drive mechanism travel that is required, and the debilitating effect of fatigue on the resilient means generally causes an eventual overall reduction in the available force. There factors thus tend to reduce the reliability of such known devices. Since the resilient force is relatively high, more durable and expensive materials are generally required by such constructions.

Also well known in the art are ribbon reversing devices that include cams which are activated by clutches of various types to disengage and engage ribbon spool drive mechanisms. There devices are necessarily complex and are accordingly subject to decreased reliability and increased construction and maintenance costs.

SUMMARY OF THE INVENTion It is an object of the present invention to provide a ribbon drive and reversing device which will furnish and maintain a constant and reliable ribbon-reversing force.

It is another object of the invention to provide a device that requires relatively light and inexpensive materials for its construction.

It is yet another object of the invention to provide a simple and reliable device which, from the standpoint of the number and complexity of parts required, is relatively inexpensive to construct and to maintain.

An important aspect of the invention is the use of a crossthreaded worm and a cooperating pivotal translator as a means of completing the translation of a unidirectionally driven ribbon drive shaft as between its two spool-driving positions, such drive shaft having been partially translated by the reversing action of one of a pair of integral worms relative to the worm wheel associated with the fully wound ribbon spool, the completed translation of the drive shaft being effective to engage the opposite of the integral worms with the worm wheel associated with the unwound spool for responsive ribbon winding thereon.

Another important aspect of the invention is the character of the cross-threaded worm and the nature of the cooperation of the pivotal translator therewith, the cross-threaded worm having a plurality of thread segments effective for translatably receiving the translator as the drive shaft is drivenly rotated, such rotation serving to translate the shaft by means of the driving effect of the thread segments against the stationary translator.

Still another aspect of the invention is the use of resilient detent means to secure the engagement of the worm and worm wheel associated with the ribbon spool upon which the ribbon is being wound, such detent means being yieldably responsive to the translation of the driven ribbon drive shaft when the ribbon is fully wound on such spool to thereafter receive the engagement of the worm and worm wheel associated with the empty spool.

BRIEF DESCRIPTION OF THE DRAWINGS These and other objects, aspects and advantages of the invention will be more clearly understood from the following description when read in conjunction with the accompanying drawings, in which:

FIG. 1 is a perspective view of a print ribbon drive and reversing device embodying features of the invention,

FIG. 2 is another perspective view of the device of FIG. 1,

FIG. 3 is a perspective view, partly in section and partially exploded, of a print ribbon spool and worm wheel assembly,

FIG. 4 is a sectional view of a print ribbon spool and worm wheel assembly taken in the direction of the arrows 44 of FIG. 3,

FIG. 5 is a side view of the cross-threaded worm and the translator shown removed from the device,

FIG. 6 is a sectional view taken in the direction of the arrows 6-6 of FIG. 5, and

FIG. 7 is a perspective view of the shaft driving mechanism shown removed from the device DETAILED DESCRIPTION OF THE INVENTION Referring to FIGS. I and 2, the print ribbon drive and reversing apparatus shown has a supporting member 10 rotatably supporting a first worm wheel I2, a section worm wheel 14, a first ribbon spool 16 and a second ribbon spool 18, and translatably supporting also a rotatable shaft 20. A first worm 22 and an oppositely threaded second worm 24 are affixed to the shaft 20, as are an ellipsoidally shaped member 26 and a corss-threaded worm 28, the member 26 comprising a first abutment 30 and a second abutment 32. Pivotally mounted in the supporting member 10 is a translator 34 which is comparably associated with the cross-threaded worm 28.

The first worm wheel 12 is operatively connected to the first ribbon spool I6 and is spaced apart from the second worm wheel 14, the latter worm wheel being operatively connected to the second ribbon spool 18. The shaft 20 is mounted tangentially adjacent the first and second worm wheels such that its longitudinal translations will alternately mesh the first worm 22 with the first worm wheel 12 and the second worm 24 with the second worm wheel 14. The ellipsoidally shaped member 26 and cross-threaded worm 28 are affixed to the shaft 20 in spaced-apart relationship and at predetermined locations thereon, such predetermined locations providing cooperating relationship with a detent plunger 36 and with the translator 34 respectively, the translator and plunger both depending from mountings disposed in an elongated frame 38 of the supporting member 10.

Referring to FIGS. 3 and 4, each of the worm wheels 12 and 14 includes a ribbon spool drive shaft 40, which extends rotatably upward through a cylindrical, bearinglike opening formed in the frame 38 and an upwardly extending collar 42 disposed in contiguous relationship with a cylindrical projection 44 depending from the frame. A compression ring 46 removably arranged on the outer surface of each of the collars 42 serves to assert a retarding drag as between the collar and the cylindrical projection 44 during rotation of the worm wheel, such drag tending to hold ribbon 48 taut on the spool from which it is being unwound. A spool-mounting plate 50 is secured to the upper extremity of the spool drive shaft 44) by means of a screw 52 and a nut 54, the screw extending throughout the shaft 40 and outwardly from the plate 50. A plurality of projections 56 formed in each spool-mounting plate 50 are slidably engageable with corresponding apertures 58 formed in the ribbon spool, for example, spools I6 and I8, a central aperture 60 of the spool being slidably and retainably accommodated by the upper extremity of the screw 52.

Referring once again to FIGS. 1 and 2, the shaft 20 is provided with a D-shaped cross section, as illustrated in FIG. 6. A sleeve 62 having a D-shaped central aperture to slidably receive the shaft 20 is rotatably mounted between a pair of shaft-supporting members 64; and first bevel gear 66 is also provided with a D-shaped central aperture to receive the shaft 20, the bevel gear 66 being provided also with an integral, similarly apertured sleeve 68 which is rotatably mounted by means of a separate pair of shaft-supporting members 64. The gear 66 is rotatably positioned between the outermost of said separate pair of shaft-supporting members and a slotted plate 70 depending from the frame 38. As previously indicated, the shaft 20 is positioned to slide tangentially adjacent the first and second worm wheels 12 and 14 respectively.

A second bevel gear 72, disposed in cooperating relationship with the first bevel gear 66, is affixed to one end of a connecting shaft 74 which is rotatably supported by a pair of supporting members 76 which also depend from the frame 38. A spur gear 78, best shown in FIGS. 2 and 7, is affixed to the opposite end of the shaft 74 and is engageable with suitable shaft-rotating means (not shown), said latter means being effective to rotate the shaft 20 in a counterclockwise direction as viewed from its left end as shown in FIG. 1.

The first worm 22 is affixed to one end of the shaft 20, and the oppositely threaded second worm 24 is affixed to the opposite -end thereof, the length of the shaft being such that when one worm, for example, worm 22, is meshed with its associated worm wheel 12, the opposite worm, for example, worm 24, is positioned beyond its associated worm wheel 14.

The ellipsoidally shaped member 26 is affixed to the shaft 20, such that the first and second abutments 30 and 32 thereof are alternately presented to the detent plunger 36 as the shaft 20 translates, the detent plunger being slidably mounted in the frame 38 and yieldably urged downwardly by a spring (not shown) into contact with the member 26.

As shown in FIGS. and 6, the pivotally mounted translator 34 is positioned by the frame 38 such that its lower portion is maintained in cooperating relationship with the crossthreaded worm 28, the pivotal axis of the translator 34 and the rotational axis of the shaft being mutually perpendicular and slightly offset one from the other. The lowermost edge of the translator is semicircular in contour to present a conforming recess for rotational cooperation with the dwell portion of the cross-threaded worm 28. This recess in the lowermost edge of the translator 34 presents a pair of downwardly directed arms 80 and 82 of predetermined difi'ering lengths, the ends of said arms presenting a semicircumferential diameter to said recess, such diameter being obtusely inclined to the pivotal axis of the translator 34. The longer of these downwardly directed arms, designated 80 in the drawings, is disposed to the rear of the shaft 20, as viewed in FIG, l, the shorter arm 82 being disposed forwardly of the rotational axis of the shaft. 4

The cross-threaded worm 28 of the preferred embodiment of the invention is comprised of six separate thread segments as would be produced by the removal of portions of the intersecting areas of the two continuous cross threads, the extremities of each thread segment being provided with a dextral and a sinistral surface, the outer surfaces of the rightward and leftward thread segments presenting dextral and sinistral threads respectively to the translator 34 when said translator is located to the right and left thereof respectively. The counterclockwise rotation of the shaft 20, as viewed form its left end as shown in FIG. 5, in combination with the rightward or leftward partial translation of the shaft, is accordingly effective to pivot the translator 34 in response to the camming action of such dextral and sinistral surfaces respectively against the arm 80, such pivoting having the efiect of steering the translator arm 82 into the grooves or cutouts between the thread segments.

The support provided the shaft 20 by the supporting members 63, and the support provided the connecting shaft 74 by the supporting members 76, are further complemented by retainers 84 slidably disposed in interiorally and transversely arranged grooves formed in the adjoining surfaces of pairs of such supporting members, said retainers being slidably insertable and removable from these grooves to thereby facilitate the assembly and disassembly of the shafts.

OPERATION OF THE DEVICE With reference to FIG. 1 and assuming that the shaft is located in its rightmost translated position as illustrated therein, with the ribbon fully wound on the spool 16, rotation of the spur gear 78 and the second bevel gear 72 in a clockwise direction will result in the counterclockwise rotation of the first bevel gear 66 and the shaft 20 (when viewed from the left end thereof).

The first worm 22, being in mesh with the first worm wheel 12, is accordingly rotated in a counterclockwise direction in such manner as would rotate the worm wheel 12 in a counterclockwise direction were it free to so rotate. Since such rotation is limited, however, by the unwound state of the spool 18, the continued rotation of the worm 22 will cause a partial leftward translation of the shaft 20 as the worm 22 screws itself out of engagement with the worm wheel 12. During this partial leftward translation, the detent plunger 36 yields to the camming force of the member 26; and the sinistral surface of the leftmost thread segment of the cross-threaded worm 28, in camming cooperation with the arm of the translator 34, serves to pivot the latter translator in a counterclockwise direction (when viewed from the top) to thereby steer the translator into the grooves or cutouts between the thread segments. As shaft 20 continues to rotate, there thread segments, in camming cooperation with the stationary translator 34, will impart a leftward translating force to the shaft 20 and the worms 22 and 24, such force being perpetuated until the translator 34 assumes a relative position rightwardly disposed of the rightmost thread segment, and the worm 24 is disposed in cooperating relationship with the second worm wheel I4. When the shaft 20 is fully translated to the left in this manner, the abutment 32 of the member 26 will thereafter cooperate with the detent plunger 36 to effectively sustain the engagement of worm 24 and the worm wheel 14. During the ensuing rotation of the shaft 20 and the worm 24, the worm wheel 14 and ribbon spool 18 are rotated in a clockwise direction to thereby wind the ribbon 48 onto the spool 18 and to unwind the ribbon from spool 16.

At such time as the ribbon is fully wound onto the spool 18 and unwound from the spool 16, the worm wheel 14 is limited from further clockwise rotation due to the connection between the leftmost extremity of the ribbon 48 and the spool 16, continued rotation of the worm 24 causing the shaft 20 to be partially translated in a rightward direction until the worm 24 is disengaged from the worm wheel 14. During this partial rightward translation, the detent plunger 36 again yields to the camming force of the member 26; and the dextral surface of the rightmost thread segment of the cross-threaded worm 28, in cooperation with the arm 80 of the translator 34, serves to pivot the latter translator in a clockwise direction (as viewed from the top) to thereby steer the translator arm 82 into the grooves or cutouts between the thread segments. As shaft 20 continues to rotate, the rotating thread segments and stationary translator 34 will impart a rightward translating force to the shaft 20 and the worms 22 and 24, such force being perpetuated until the translator 34 assumes a relative position leftwardly disposed of the leftmost thread segment, and the worm 22 is disposed in cooperating relationship with the first worm wheel 12. When the shaft is fully translated in this manner, the abutment 30 of the member 26 will thereafter cooperate with the detent plunger 36 to effectively sustain the engagement of the worm 22 and the worm wheel 12. During the ensuing rotation of the shaft 20 and worm 22, the worm wheel 12 and ribbon spool 16 are rotated in a counterclockwise direction tothereby wind the ribbon 48 onto the spool 16 and to unwind the ribbon from the spool 18. This process is repeated as the ribbon 48 is alternately wound onto each of the spools, the shaft 20 being alternately translated as between its two ribbon winding positions as above described, such translations being partially effectuated by the screwing action of the worms 22 and 24 out of engagement with their corresponding worm wheels, and being completed by the driving effect of the rotating thread segments of the cross-threaded worm 28 against the pivotally stationary translator 34.

While the print-ribbon-reversing apparatus has been shown and described in considerable detail, it should be understood that many changes and variations may be made therein without departing from the spirit and scope of the invention.

What is claimed is:

I. Translatable coupling means comprising:

first and second spaced-apart driven means for winding an operably interconnecting web alternately and respectively therebetween;

driving means disengageably responsive to maximum web transfer for alternately driving said first and said second driven means;

supporting means for effectively mounting said first and said second driven means and said driving means;

cross-threaded, screw-type translating means associated with said supporting means and with said driving means for coupling said latter means to an unwound one of said driven means upon disengagement from a wound one of said driven means; and

detent means for effectively and alternately maintaining said driving means in coupled relationship with said first and said second driven means, said detent means having an ellipsoidally shaped member and a detent plunger yieldably urged into cooperation therewith, said ellipsoidally shaped member alternately presenting a first and a second abutment to said detent plunger in response to maximum web transfer between said first and said second driven means.

2. The translatable coupling means defined by claim 1 wherein:

said driving means has a first and a second worm affixed to opposite ends of a translatable and rotatable shaft positioned tangentially adjacent said first and said second drive means, said shaft having a linear dimension in excess of said spaced-apart distance between said first and said second driven means such that said first and said second worms are alternately engageable with said first and said second driven means as said translatable shaft translates; and

said translating means has a translator member pivotally mounted on said supporting means and cooperating with a cross-threaded worm operatively connected to said rotatable and translatable shaft of said driving means, the cooperation of said translator member with said crossthreaded worm being of an engageable nature and semicircumferential in character, the diametric axis of said semicircumferential engagement of said translator member being obtusely inclined to the pivotal axis of said translator member, thereby forming a pair of engaging arms of predetermined differing length.

3. The translatable coupling means defined by claim 2 wherein the longer of said engaging arms is disposed opposite the pivotal axis of said translator member and opposite the rotational axis of said cross-threaded worm from the shorter of said engaging arms and is the arm farthest disposed from said pivotal axis.

4. A print ribbon drive and reversing device comprising:

first rotatable ribbon storing means for alternately accepting and dispensing print ribbon terminally attached thereto;

second rotatable ribbon storing means for alternately accepting and dispensing print ribbon terminally attached thereto and to said first ribbon storing means;

drive means for alternately rotating said first and said second ribbon storing means;

supporting means for effectively mounting said first and said second ribbon storing means and said drive means; and

drive translating means mounted on said supporting means for alternately coupling said drive means to said first and said second ribbon storing means, said drive translating means including a rotatable cross-threaded worm and a pivotable translator, said rotatable cross-threaded worm and said pivotable translator of said drive translating means being cooperatively engageable, said engagement being semicircumferential in character, the diametric axis of said semicircumferential engagement of said translator being obtusely inclined to the pivotal axis of said translator, thereby forming a pair of engaging arms of predetermined differing length.

5. The print ribbon drive and reversing device defined in claim 4 wherein the longer of said engaging arms is disposed opposite the pivotal axis of said translator and opposite the rotational axis of said cross-threaded worm from the shorter of said engaging arms and IS the arm farthest disposed from said pivotal axis.

6. The print ribbon drive and reversing device defined by claim 4 wherein said drive means has a pair of worm wheels operatively connected to said first and said second ribbonstoring means, a translatable shaft disposed tangentially adjacent said pair of worm wheels, said shaft being unidirectionally rotatable, a pair of oppositely threaded and spaced-apart worms affixed to the outer extremities of said shaft to alternately rotate said worm wheels and said first and said second ribbon storing means in opposite directions to thereby wind print ribbons alternately onto each of said first and said second ribbon storing means, said worms being cooperatively and respectively associated with said pair of worm wheels such that one worm is disengaged from and outwardly disposed of its associated worm wheel when the opposite of said worms is cooperatively engaged with the other of said worm wheels; and additionally having detent means for effectively maintaining one of said worms in coupled relationship with an associated one of said worm wheels, said detent means having an ellipsoidally shaped member and a detent plunger yieldably urged into cooperation therewith, said ellipsoidally shaped member alternately presenting a first and a second abutment to said detent plunger in response to maximum ribbon transfer as between said first and said second rotatable ribbon-storing means. 

1. Translatable coupling means comprising: first and second spaced-apart driven means for winding an operably interconnecting web alternately and respectively therebetween; driving means disengageably responsive to maximum web transfer for alternately driving said first and said second driven means; supporting means for effectively mounting said first and said second driven means and said driving means; cross-threaded, screw-type translating means associated with said supporting means and with said driving means for coupling said latter means to an unwound one of said driven means upon disengagement from a wound one of said driven means; and detent means for effectively and alternately maintaining said driving means in coupled relationship with said first and said second driven means, said detent means having an ellipsoidally shaped member and a detent plunger yieldably urged into cooperation therewith, said ellipsoidally shaped member alternately presenting a first and a second abutment to said detent plunger in response to maximum web transfer between said first and said second driven means.
 2. The translatable coupling means defined by claim 1 wherein: said driving means has a first and a second worm affixed to opposite ends of a translatable and rotatable shaft positioned tangentially adjacent said first and said second drive means, said shaft having a linear dimension in excess of said spaced-apart distance between said first and said second driven means such that said first and said second worms are alternately engageable with said first and said second driven means as said translatable shaft translates; and said translating means has a translator member pivotally mounted on said supporting means and cooperating with a cross-threaded worm operatively connected to said rotatable and translatable shaft of said driving means, the cooperation of said translator member with said cross-threaded worm being of an engageable nature and semicircumferential in character, the diametric axis of said semicircumferential engagement of said translator member being obtusely inclined to the pivotal axis of said translator member, thereby forming a pair of engaging arms of predetermined differing length.
 3. The translatable coupling means defined by claim 2 wherein the longer of said engaging arms is disposed opposite the pivotal axis of said translator member and opposite the rotational axis of said cross-threaded worm from the shorter of said engaging arms and is the arm farthest disposed from said pivotal axis.
 4. A print ribbon drive and reversing device comprising: first rotatable ribbon storing means for alternately accepting and dispensing print ribbon terminally attacHed thereto; second rotatable ribbon storing means for alternately accepting and dispensing print ribbon terminally attached thereto and to said first ribbon storing means; drive means for alternately rotating said first and said second ribbon storing means; supporting means for effectively mounting said first and said second ribbon storing means and said drive means; and drive translating means mounted on said supporting means for alternately coupling said drive means to said first and said second ribbon storing means, said drive translating means including a rotatable cross-threaded worm and a pivotable translator, said rotatable cross-threaded worm and said pivotable translator of said drive translating means being cooperatively engageable, said engagement being semicircumferential in character, the diametric axis of said semicircumferential engagement of said translator being obtusely inclined to the pivotal axis of said translator, thereby forming a pair of engaging arms of predetermined differing length.
 5. The print ribbon drive and reversing device defined in claim 4 wherein the longer of said engaging arms is disposed opposite the pivotal axis of said translator and opposite the rotational axis of said cross-threaded worm from the shorter of said engaging arms and is the arm farthest disposed from said pivotal axis.
 6. The print ribbon drive and reversing device defined by claim 4 wherein said drive means has a pair of worm wheels operatively connected to said first and said second ribbon-storing means, a translatable shaft disposed tangentially adjacent said pair of worm wheels, said shaft being unidirectionally rotatable, a pair of oppositely threaded and spaced-apart worms affixed to the outer extremities of said shaft to alternately rotate said worm wheels and said first and said second ribbon storing means in opposite directions to thereby wind print ribbons alternately onto each of said first and said second ribbon storing means, said worms being cooperatively and respectively associated with said pair of worm wheels such that one worm is disengaged from and outwardly disposed of its associated worm wheel when the opposite of said worms is cooperatively engaged with the other of said worm wheels; and additionally having detent means for effectively maintaining one of said worms in coupled relationship with an associated one of said worm wheels, said detent means having an ellipsoidally shaped member and a detent plunger yieldably urged into cooperation therewith, said ellipsoidally shaped member alternately presenting a first and a second abutment to said detent plunger in response to maximum ribbon transfer as between said first and said second rotatable ribbon-storing means. 